1. Field of the Invention.
This invention relates generally to a portable machining lathe, and more particularly a split frame clamshell-type portable machining lathe for cutting and finishing relatively large diameter pipes that has a hinge arrangement for joining two semicircular segments one to the other.
2. Description of the Prior Art.
Split frame clamshell lathes of the type described herein are known in the art. My earlier U.S. Pat. Nos. 4,739,685, 4,939,964, and 5,549,024 are illustrative of the technology involved. These patents are hereby incorporated by reference. As described in these three patents, the clamshell machining lathe generally comprises first and second semicircular segments that are designed to be joined together to form an annular assembly for encircling a shaft or pipe to be machined. The assembly includes a stationary ring, and a rotatable ring abutting the stationary ring. The rotatable ring includes a spur gear on its peripheral surface and is journaled to the stationary portion for rotation about a concentrically disposed pipe or shaft to be machined. A motor is attached to the stationary assembly and includes a drive gear designed to mesh with the spur gear on the rotatable segment of the pipe lathe. Also, a tool block for supporting a cutting tool is mounted on the rotatable segment. The cutting tool is adapted to be advanced in incremental steps in a radial direction against the pipe to be machined upon each orbit of the ring gear about the workpiece.
A problem has heretofore existed in the prior art in the manner in which the semicircular segments are connected to one another. In the past, splice plates have been used to connect the two pieces together. This has made set-up of the clamshell lathe on the workpiece difficult. Generally at least two workers are needed to mount the clamshell lathe onto the workpiece. They must simultaneously lift and hold the semicircular segments onto the workpiece while they bolt the clamping plates in place to join the mating ends of the semicircular segments to one another. It is the purpose of the present invention to simplify the initial set-up such that only a single person is required to perform the mounting operations.
The present invention comprises a portable machining lathe for machining a pipe or similar workpiece. The lathe includes two semicircular segments having a stationary section and a rotatable section. The two semicircular segments are cooperatively connected by a hinge system on one end, and steel spice plates on the other. The hinge on the stationary section of each has a top bracket and bottom bracket. On the rotatable section of each member there is a male hinge clamp and a female hinge clamp that are cooperatively connected such that when the hinge is closed, the two semicircular segments form a complete annulus. Splice plates cooperatively connect the non-hinged ends of the two semicircular segments A particular advantage of the present invention is that the lathe of the present invention is relatively portable. Furthermore, the substitution of an especially designed hinge for one of the sets of spice plates minimizes the manhandling and allows the lathe to be mounted on a cylindrical workpiece and operated by one person.
Another feature of the present invention is that the pipe lathe is capable of being affixed to the pipe in a relatively simple manner, and the operation of the lathe requires minimal time.
For a better understanding of the invention, and of the advantages obtained in its use, reference should be made to the drawings and the accompanying descriptive material, in which there is illustrated and described a preferred embodiment of the invention.